The present invention relates to improvements in a control system of a continuously variable transmission (CVT) for a vehicle, and more particularly to a control system of a belt type CVT.
A Japanese Patent Provisional Publication No. 8-74959 discloses a line pressure control system for a belt type CVT. The conventional line pressure control system is arranged to control a duty valve by outputting a duty ratio indicative signal as a command value to the duty valve in order to control a belt holding force of the pulley of the CVT. The command value to the duty valve is limited within a range except dead zones so as to ensure the responsibility of the line pressure applied to the CVT.